The present invention relates to the cleaning of spraying apparatus such as spray painting guns and similar equipment. In one aspect it relates to apparatus for use in such cleaning operations. In another aspect it relates to a method of cleaning.
A conventional spray painting gun has respective inlets for supplies of compressed gas (usually air) and liquid paint. These are mixed at the outlet of the gun, and emerge as a fine spray. It is periodically necessary to clean the gun. The normal method used is simply to pass a cleaning solvent through the paint inlet, by filling the paint container with the solvent. The solvent is then sprayed in the same manner as paint, using the compressed gas supply. This is rather wasteful of both solvent and gas. Furthermore, the expelled solvent must be captured, since it will rarely be acceptable to spray it into free air. Normally a paint spray booth has means for trapping sprayed paint, often involving mixing the spray with water treated with a chemical additive. However, the usual additives are rendered ineffectual by the admixture of significant quantities of the cleaning solvent. Thus before the booth can be returned to paint spraying, the additive must be replaced, if the continued use of the booth is not to lead to an unacceptable residue and the eventual discharge of pollutants.
A further disadvantage of the known technique is that the operator has to be present, holding the gun.
GB-A No. 2 095 586 discloses means for cleaning a spray apparatus that uses a centrifugal atomiser. This is moved so that it can spray into a bowl-shaped receptacle, relative to which it must be carefully positioned. Some paint is likely to escape. The arrangement is rather cumbersome, and is only suitable for the particular type of spray apparatus.
Preferred embodiments of the present invention allow some or all of these disadvantages to be ameliorated.